The first prototype is running by about three days and after some revisions on the Arduino software (mostly on the calculation algorithms) it works fine, ready for the public.
Arduino uno R3
5kg max load sensor
Mx711 chip analog to digital sensor amplifier
A very small circuit with two buttons and a dip-switch
16×2 alphanumeric LCD monochrome display
Orange LED (shows the load sensor readings when flashing)
Easy to use
The Arduino script has been done to make the use of the tool while 3D printing; it works in a semi-automatic mode and does not need calibration or settings. One of the most interesting aspects is the ability to manage automatically the filament roll also if it is not on start. Then you can change it (e.g. changing the filament colour or material) and the system continue working.
What you should know
Before starting using the filament monitor you need to know the empty roll weight. This is the only fixed variables that can’t be calculated or deducted internally. Knowing this value is easy and you do not need to have an empty roll, obvious! If you weight on a digital scale (possibly one for kitchen more precise than a bigger one) you see that the 1Kg filament roll weight some more, e.g. 120 Gr. This is the weight of your roll that should be setup as the filament tare.
You should also know: Material (PLA or ABS are supported), filament diameter and full roll weight. These values should be preset through the three dip-switches as shown in the following table:
Meaning Off On
Material PLA ABS
Diameter 1.75mm 3mm
Weight 1kg 2kg
Power-on the support without the filament roll and wait for the display showing Started, The system is self-calibrated to the internal zero point.
Put the filament roll on the rotating support and press the control button. Arduino calculates the effective weight, deduct the filament tare and enter in the Ready state: remaining meters and percentage of filament as shown too
Press the control button again; it enters in the Load state and you can start printing!
Pressing the second button you switch between grams and centimeters the constantly updated value of the consumed filament on the second line. The first line instead shows the remaining meters and the used percentage.
Note: as the length in centimeters reach the value 100 (1 meter) the displayed value is shown in meters instead.
First of all we should consider the following points:
For obvious reasons of easy pricing the plastic of 3D printing filament is sold and managed at source on a weight based. Despite it is distributed in form of filament, useful for the 3D printers. The most common diameters are 1.75 and 3 mm thick.
3D printers – especially the slicers algorithms – calculates the printing time based on the – average – Extruder speed integrated with the filament diameter, the nozzle size and the layer thickness. It has sense because as a matter of fact the physics of the slicer is calculating a solid 3D object divided in slices where the speed as well as extrusion temperature impact on the final quality. So while doing the slicing calculations it is easy and useful to collect the number of meters needed to 3D print a certain object.
Depending on the material we use filament has different performances; I mean same weight corresponds to different metering of the roll (filament diameter makes the difference)
We know – or it is easy to know the specific weight of the materials, e.g. PLA and ABS have different specific weights: one meter of PLA has different weight than one meter of ABS, same diameter. A good value can be obtained by the filament calculator
The entire process to measure weight and lenght of the filament (used, remaining etc.) should be cheap and easy and efficient too
Asking for external – producers/distributors – help making complex changes is senseless. We have a problem and we should solve it. Not change the world to avoid the problem.
Considering the above points the right approach for a dynamic measuring of the 3D printers filament usage is surely weight-based.
Now the 3D Printer Filament Monitor integrates this support with a weight sensor creating an Arduino based device for real-time filament monitoring. Also in this case the entire structure is fully 3D printed and the images below shows how it is built.
Recently I followed with a certain interest a project trying to calculate the 3D printers filament consumption during jobs. The ReFILL agent project first published on Hackster.io bases the calculation on the number of rotations of the filament roll detected by an RFID sensor. Then when the filament is near to finish an automatic order can be sent to amazon for replacement.
To be honest the idea has not convinced me too much because it is too complex to manage (every roll should be modified by the user adding a printed RFID tag and the measure is subject to a too big systematic error.
As I have explained in my comments on the Element14 blog post ReFILL-ament for3D printersthe base principle is not correct and the systematic error is amplified and distributed up to the finished project.
To manage the math of the filament we should start from a different approach, not the too effimere roll rotation approach. This is the reason I started the 3D printer filament monitor project a couple of weeks ago.
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